The present invention relates to a recording/reproducing apparatus and to an input/output device for performing digital compression/expansion of input analog video signals or the like; and, more particularly, the invention relates to compression/expansion processing and to a suitable processing technique for using copy guard data or character data in that processing.
In the typical household analog VTR of the prior art, the problem of preventing people from making illegal copies or the like has become more and more serious as the number of soft tapes increases. From the standpoint of copyright protection, the making of unauthorized copies has been prevented by superimposing pseudo-sync pulses as a copy guard signal over a vertical blanking period to promote a malfunction (in compressions) of an AGC (Automatic Gain Control) circuit at the time of dubbing using the VTR, thereby to significantly disturb reproduction of a recorded picture.
To a soft disc conforming to the DVD (Digital Video Disc) standards determined in recent years, on the other hand, there are added not only the aforementioned pseudo-sync pulses, but also a copy guard signal called a xe2x80x9cColorstripexe2x80x9d. In a device, such as a VTR having a system for synchronizing a signal used as a reference for color signal processing with a burst signal inputted at the recording time, the Colorstripe will invert the color burst signal by 180 degrees in phase at a constant interval of lines in the vicinity of the burst center. This inversion disturbs the hue seriously so as to cause a hue defect in the form of transverse stripes so that a protection of the copyright for the recorded data may be achieved.
These copy preventing functions are effective in an analog VTR, but not in a digital VTR or the like. However, Japanese Patent Laid-open No. Hei 9-102929 discloses a technique which is capable of preventing the copying of proprietary data even between digital VTRs. According to this technique, a disturbing signal, such as the pseudo-sync pulses or the Colorstripe signal, is latched in an area which is retained by erecting a disturbing signal flag, and a disturbing signal at a reproducing time is restored on the basis of the flag, so that flag can be transmitted even during signal transfer through a digital interface to effect copy prevention.
Of the household digital VTRs produced in recent years, on the other hand, there has been produced a floor VTR based on DV standards using a magnetic tape of 6 mm width. This floor VTR elongates the recording time period by using a picture compression/expansion technique, and this compressing/expanding digital VTR is expected to be a main component of the household in the future. There has also been produced a VTR which is given enhanced compatibility over the existing analog VTR by adding a new digital VTR mode to the existing household analog VTR mode. There is also a VTR which covers a digital broadcasting program to record a bit stream signal from a digital tuner (IRD) as it is. The signals to be obtained from the digital tuner contain many types of data, such as character data, and many digital VTRs can produce a highly fine OSD screen with such data using a digital OSD (On Screen Display) circuit, unlike the existing analog VTR.
The known types of digital VTR thus far described include a copy preventing technique based on compression/expansion, but the industry has failed to provide a household VTR utilizing that technique. In other words, there has not been a household VTR exploiting the compression/expansion technique. Moreover, that prior art example has made use only of a copy guard signal, but not of the recording processing of a closed caption signal (of character data) to be superimposed over a vertical blanking period in a digital device nor of the reproduction of such data from the digital device.
Generally, in a recording/reproducing apparatus, such as a VTR, on the other hand, an EE (i.e., the output having passed through only an electric path to a monitor) screen is outputted to a monitor TV even during the recording mode of operation. In a digital device utilizing a digital compression/expansion technique, the quality of a picture (considerably varied by the compression) to be recorded in the recording/reproducing apparatus has to be checked to monitor the recording picture quality, because of the differences from the EE picture quality being monitored. On the other hand, consideration has to be given to a specific processing of the data, such as the copy guard signal processing, superimposed over the vertical blanking period, in the EE output signal at the aforementioned time of checking the picture quality.
In a digital device utilizing a digital compression/expansion technique, moreover, the quality of the picture to be recorded in the recording/reproducing apparatus is hard to manage due to the change in the recording transmission rate. In order to provide a recording/reproducing apparatus of excellent cost performance, on the other hand, the aforementioned highly fine OSD circuit has to be effectively utilized not only for bit stream recording, but also for external video input recording or for signal reproduction, but no application for this has been disclosed.
Moreover, there may be a soft tape of a VTR which contains copy guard data in the form of only pseudo-sync pulses, or a soft tape in which the copy guard data is partially deficient, as is the case of an illegal apparatus, such as a copy guard signal eliminating apparatus. Thus, it is necessary to ensure the copy guard function sufficiently, even with use of only one of the pseudo-sync pulses or the Colorstripe signal.
An object of the invention is to solve those problems and to provide a recording/reproducing apparatus and an input/output device which are characterized in that they employ the compression/expansion technique to realize protection of character data and a copy guard signal, as well as an effective utilization of a highly fine OSD circuit, thereby to achieve a satisfactory cost performance and a high picture quality.
In order to achieve the above-specified object, according to the invention, there is provided a recording/reproducing apparatus comprising: a converter which converts a received analog video signal into a digital signal; a recorder which records the converted digital signal on a recording media; a reproducer which reproduces a digital signal from the recording media; and a converter which converts the reproduced digital signal into an analog video signal, wherein the improvement comprises: a detector which detects the character data, which is superimposed over a vertical blanking period of the analog video signal, at the time of recording; and a superimposer which encodes said detected character data and superimposes the encoded character data over a digital signal from which said character data has been removed, whereby the superimposed signal is recorded on the recording media.
Further, in accordance with the invention, there is provided a recording/reproducing apparatus comprising: a converter which converts a received analog video signal into a digital signal; a recorder which records the converted digital signal on a recording media; a reproducer which reproduces a digital signal from the recording media; and a converter which converts the reproduced digital signal into an analog video signal, wherein the improvement comprises: an extractor which extracts character data from the digital signal which is read out from the recording media at the reproducing time; and an adder which adds the extracted character data to a predetermined position in the reproduced digital video signal, whereby the analog video signal converted from the digital video signal by said converter is outputted.
Further, in accordance with the invention, there is provided a recording/reproducing apparatus comprising: a converter which converts a received analog video signal into a first digital signal; a compressor which compresses the first digital signal to form a compressed digital signal; a recorder which records the compressed digital signal on a recording media; a reproducer which reproduces the compressed digital signal from the recording media; and an expander which expands the compressed digital signal, wherein the improvement comprises: a switcher which switches the first digital signal and the compressed digital signal; and a converter which converts the output of the switcher into an analog video signal, whereby the converted analog video signal is outputted to a picture display device.
Moreover, in accordance with the invention, on the other hand, there is provided a recording/reproducing apparatus comprising: a converter which converts a received analog video signal into a digital signal; a compressor which compresses the converted digital signal; a recorder which records the compressed digital signal on a recording media; a reproducer which reproduces the compressed digital signal from the recording media; and an expander which expands the compressed digital signal, wherein the improvement comprises: a converter which converts a compressed/expanded digital signal into an analog video signal; and a switcher which switches the analog signal before being converted into a digital signal and a compressed/expanded second analog signal, whereby the analog video signal is displayed in a picture display device, and wherein the improvement further comprises: a detector which detects data, which is superimposed over a vertical blanking period to be deleted in the process of compression/expansion, at an upstream side of the compressor; a superimposer which encodes and superimposes said detected data over said compressed signal; and an adder which extracts said superimposed data and adds the extracted data to the signal expanded by the expander, whereby the output obtained from said adder is obtained as said second analog signal. Here, the data extracted by said detector is preferably sent through a microcomputer to said adder.
Further, in accordance with the invention, on the other hand, there is provided a recording/reproducing apparatus comprising: a converter which converts a received analog video signal into a digital signal; a compressor which compresses the converted digital signal; a recorder which records the compressed signal on a recording media; a reproducer which reproduces the digital signal from the recording media; and an expander which expands the compressed signal, said apparatus having a recording/reproducing digital mode and an analog mode for recording/reproducing the received analog video signal in an analog state, wherein the improvement comprises: a converter which converts a compressed/expanded digital signal into an analog video signal; and a switcher which switches a first analog signal before being encoded and a compressed/expanded analog signal, whereby the analog video signal is displayed in a picture display device, and wherein the improvement further comprises: a detector which detects data, which is superimposed over a vertical blanking period to be deleted in the process of compression/expansion, at an upstream side of the compressor; a superimposer which encodes and superimposes said detected data over said compressed signal; and an adder which extracts said superimposed data and adds the extracted data to the signal expanded by the expander, whereby the output obtained from said adder is obtained as said second analog signal.
Here, said compressor preferably has a variable transmission rate, and said second analog signal is preferably utilized as a check mode for executing the optimum setting of said transmission rate for influencing the picture quality.
Further, in accordance with the invention, a digital OSD (On Screen Display) screen is produced at the downstream side of said expander, whereby at the reproducing time in the digital mode, at the time of inputting an external composite signal and at the reproducing time in the analog mode, said second analog signal compressed/expanded at all times is fixed at an output so that a digital OSD screen is displayed in a picture display device.
Further, in accordance with the invention, the path for obtaining said second analog signal includes: a video decoder which decodes the analog video signal into a luminance signal and a color difference signal; a compressor which compresses the output of the video decoder; an expander which expands the compressed signal; an adder which adds said data; and a video encoder which converts the output of the adder into an analog video signal, and at the downstream side of said expander, there is arranged a switch circuit which switches the output of said video decoder and the output of the expander, and there is arranged a digital OSD circuit at the downstream side of the switch circuit, whereby one compressed/expanded signal passing at all times through the digital OSD circuit and the vide decoded/encoded signal can be switched as said second analog signal.
Moreover, in accordance with the invention, there is provided a recording/reproducing apparatus comprising: an AD converter which converts an input analog video signal into a digital signal; a compressor which compresses the output of said AD converter; a recorder which records the output of said compressor on a recording media; a reproducer which reproduces the digital signal from said recording media; an expander which expands the output of said reproducer; and a DA converter which converts the output of said expander into analog video signal, wherein the improvement comprises: a detector which detects first copy guard data superimposed over a vertical blanking period of said input analog video signal and second copy guard data superimposed over a color burst signal; and an adder which adds said first and second copy guard data detected by said detector to the signal expanded by said expander, whereby the output of said compressor is fed to said expander in modes other than the reproducing mode by said reproducer.
Here, the copy guard data extracted by said detector os preferably sent through a microcomputer to said adder. The microcomputer preferably adjusts a delay in the signal, caused in said compression/expansion process, and a delay in the copy guard data extracted by said detector. On the other hand, said second copy guard data is preferably detected on the basis of the signal which is demodulated from an incoming modulated color signal with respect to a B-Y axis.
The recording/reproducing apparatus further comprises: an analog recorder which records the received analog video signal on the recording media as it is in the analog state; and an analog reproducer which reproduces the analog signal from said recording media. The second copy guard signal is preferably detected on the basis of the data from an APC (Auto Phase Control) circuit, contained in said analog recorder for phase-locking the color burst signal contained in the input analog video signal and a color subcarrier to be used as a reference signal of said analog recorder.
Further, in accordance with the invention, there is provided a recording/reproducing apparatus comprising: an AD converter which converts an input analog video signal into a digital signal; a compressor which compresses the output of said AD converter; an expander which expands the compressed signal; and a DA converter which converts the output of said expander into an analog video signal, wherein the output of said compressor is fed to said expander, and wherein the improvement comprises: a detector which detects first copy guard data superimposed over a vertical blanking period of said input analog video signal and second copy guard data superimposed over a color burst signal; and an adder which adds said first and second copy guard data detected by said detector to the signal expanded by said expander.